There are numerous connector keying arrangements which permit the insertion of a circuit board into only a predefined connector. These connector keying arrangements rely on apparatus configurations which are unique for each circuit board/control combination and which apparatus requires the modification of both the circuit board and the connector. An example of this type of connector keying arrangement is illustrated in U.S. Pat. No. 3,404,362 issued Oct. 1, 1968 to D. Amendola. The Amendola patent describes selective indexing apparatus comprising an index bracket which is attached to the circuit board and a corresponding index guide which is attached to the connector. Coding pins are attached to each connector index guide and corresponding holes are drilled through the index bracket of the associated circuit board so that only the particular circuit board can be inserted into the corresponding connector. All other circuit boards will be blocked from insertion into the connector by the index pins on the index guide not mating with corresponding holes on the index bracket of the circuit board.